This invention relates to high speed printers and more specifically to belt or chain printers using a nonmetallic belt and detachable letter or character carriers.
Early high speed printers generally used a rotating drum as the letter or character carrier. In drum printers, the letters or characters are arranged in columns around the drum and the drum rotates in such a manner that the characters travel in a vertical direction with respect to the print line. Any misregistration of characters at the time of print causes a vertical offset of the letter which is very noticeable and offensive to the eye.
In the chain or belt printer, the characters are carried in a horizontal direction and any misregistration is less noticeable and therefore, less offensive. Chain printers at first used metal belts or chains and carriers. These metal belts require lubrication to prevent wear and to operate properly. However, even with extensive lubrication the metal to metal contact causes excessive wear and in addition dust including paper dust interferes with the lubrication. In order to overcome the lubrication problems, nonmetallic belts were developed.
With both the metal and nonmetal belts, several different methods have been devised to attach the letter or character carriers to the belt. All these prior art methods require some securing means for holding the letter or character carriers on the belts. For example, bolts have been used to secure the carrier to the belts as described in U.S. Pat. No. 3,041,964, to Simpson et al. and spring clips have been used to hold a carrier that is clipped over the belt as described in U.S. Pat. No. 3,379,125 to Antonucci. Of course, other methods have also been utilized. In all these methods, some separate securing means are required to hold the carrier on the belt.
This invention provides a plastic carrier that is clipped on the belt and held on the belt without separate fastening or securing means. The carriers are two characters or letters wide and are readily attached to or removed from the belt. No bolts, clips or other securing means are required. The carrier is a single piece carrier made of self-lubricating plastic. The belt used with the carriers is a glass reinforced rubber belt.